Synchronizing external electrical activity

ABSTRACT

Systems and methods are described herein for use in synchronizing electrical activity monitored by a plurality of external electrodes with supplemental cardiac data for use in evaluating a patient&#39;s cardiac condition and configuring cardiac therapy. The supplemental cardiac data may include one or more markers indicative of the occurrence of cardiac events and/or data representative of representative of at least one of cardiac electrical signals, cardiac sounds, cardiac pressures, blood flow, and an estimated instantaneous flow waveform provided by a left ventricular assist device.

The present application claims the benefit of U.S. ProvisionalApplication No. 62/913,030, filed Oct. 9, 2019, which is incorporatedherein by reference in its entirety.

The disclosure herein relates to systems and methods for use insynchronizing electrical activity monitored by a plurality of externalelectrodes with supplemental cardiac data for use in evaluating apatient's cardiac condition and configuring cardiac therapy.

Systems for configuring medical devices and evaluating a patient'scardiac condition may include workstations or other equipment inaddition to the implantable medical device itself. In some cases, theseother pieces of equipment assist the physician or other technician withplacing the intracardiac leads at particular locations on or in theheart. In some cases, the equipment provides information to thephysician about the electrical activity of the heart and the location ofthe intracardiac lead.

SUMMARY

The illustrative systems and methods described herein may be configuredto assist a user (e.g., a physician) in evaluating and configuringcardiac therapy (e.g., cardiac therapy being performed on a patientduring and/or after implantation of cardiac therapy apparatus). In oneor more embodiments, the electrode apparatus of the systems and methodsmay be described as being noninvasive because such electrode apparatusmay take electrical measurements noninvasively using, e.g., a pluralityof external electrodes attached to the skin of a patient about thepatient's torso.

The illustrative systems and methods may be described as beingconfigured to link implantable cardiac device marker data and other datawith external sensor instruments or another implantable device.Integrating implantable cardiac device markers with external sensorinstruments may have many different applications in enhancing variouscapabilities for better detection and diagnosis. For example,implantable cardiac devices may include sense amplifiers for detectingintrinsic activities in different chambers of the heart as well astiming markers for delivery of pacing by one or more leads or devices tocertain chamber(s) of the heart. Synchronization of the data with anexternal sensor system and instrument may help in detection andsubsequent diagnosis.

For instance, the “ECG belt” is an external surface mapping systemcomprising multiple external ECG sensors/electrodes positioned on apatient's torso. Knowing the timing of a ventricular pacing event fromthe device (e.g., left ventricular pacing) may help the external surfacemapping system “blank out” or have other ways of eliminating data for acertain time period after pacing (e.g., 5 ms) to eliminate potentialartifacts in the external electrical signals. Further, it can also helpdetect beginning of depolarization (QRS) complexes during ventricularpacing as well as ventricular sensing from the device. Other implantabledevice data (e.g. pace programming parameters) may be also integratedduring recording and/or processing of external sensor (in this case,ECG) data to help annotate the data.

The illustrative systems and methods may be configured to synchronize anexternal sensor system (e.g., ECG belt system) with marker timing andother programming data from an implantable cardiac device (e.g., acardiac resynchronization therapy device). Further, the illustrativesystems and methods may use marker data (e.g., atrial sensing AS, atrialpacing AP, ventricular sensing VS, ventricular pacing VP, effectivecapture E, ineffective capture I) to annotate parts of ECG recordings bythe external sensor system and to aid in detection and diagnosis. Forexample, QRS onset detection may be augmented based on VP/VS markers.Further, for example, pacing artifacts may be avoided by blanking orother means for a certain time period (e.g., about 5 milliseconds (ms)to about 10 ms) after delivery of ventricular paces, especially leftventricular paces. Still further, for example, cardiac cycles/eventslabeled as VS or ineffective pace (I) by the device may be eliminated,or “ruled out,” when processing electrical heterogeneity information(e.g., dyssynchrony information) during LV pacing or biventricularpacing.

The illustrative systems and methods could also annotate external sensordata to mark various certain cardiac events such as, e.g., atrialdepolarization based on AS/AP markers, ventricular depolarization basedon VP, VS markers, difference in timing between an A-event and the nextsucceeding V event to mark an AV interval, etc. Further, theillustrative systems and methods could combine ECG activity monitored bya plurality of external electrodes with non-ECG sensor data like anexternal pressure sensor data or an external acoustic sensor data tovisualize and calculate timing of device sensing or pacing with respectto timing of certain mechanical events like closing of heart valves orstart of ventricular systole, diastole, etc. Still further, theillustrative systems and methods could also synchronize ECG activitymonitored by a plurality of external electrodes with data from anotherimplantable device (e.g., waveforms from a left ventricular assistdevice (LVAD). Then, the illustrative systems and methods may be used toadjust cardiac therapy based on electro-mechanical timings provided bythe supplemented ECG activity. For example, pacing parameters may beoptimized to shorten the interval between timing of delivery of pacingand start of systole or maximize ejection time (e.g., duration ofsystole).

One illustrative system for use in cardiac evaluation may includeelectrode apparatus comprising a plurality of external electrodes tomonitor electrical activity from tissue of a patient, a communicationinterface to receive cardiac information from at least one medicaldevice, and a computing apparatus comprising processing circuitry andoperably coupled to the electrode apparatus and the communicationinterface. The computing apparatus may be configured to monitorelectrical activity using the plurality of external electrodes, receivesupplemental cardiac data from at least one medical device via thecommunication interface, and synchronize the monitored electricalactivity or data based on the monitored electrical activity to thesupplemental cardiac data resulting in synchronized cardiac information.

One illustrative method for use in cardiac evaluation may includemonitoring electrical activity from tissue of a patient using aplurality of external electrodes, receiving supplemental cardiac datafrom at least one medical device, and synchronizing the monitoredelectrical activity or data based on the monitored electrical activityto the supplemental cardiac data resulting in synchronized cardiacinformation.

One illustrative system for use in cardiac evaluation may includeelectrode apparatus comprising a plurality of external electrodes tomonitor electrical activity from tissue of a patient, a communicationinterface to receive cardiac information from at least one medicaldevice, a display comprising a graphical user interface to presentinformation for use in assisting a user in at least one of assessing apatient's cardiac health and evaluating and adjusting cardiac therapydelivered to a patient, and a computing apparatus comprising processingcircuitry and operably coupled to the electrode apparatus and thecommunication interface. The computing apparatus may be configured tomonitor electrical activity using the plurality of external electrodes,receive supplemental cardiac data from at least one medical device viathe communication interface, synchronize the monitored electricalactivity or data based on the monitored electrical activity to thesupplemental cardiac data resulting in synchronized cardiac information,and display, on the graphical user interface, at least part of themonitored electrical activity or data based thereon annotated with atleast part of the supplemental cardiac data.

The above summary is not intended to describe each embodiment or everyimplementation of the present disclosure. A more complete understandingwill become apparent and appreciated by referring to the followingdetailed description and claims taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an illustrative system including electrodeapparatus, display apparatus, and computing apparatus.

FIGS. 2-3 are diagrams of illustrative external electrode apparatus formeasuring torso-surface potentials.

FIG. 4 is a block diagram of an illustrative method of providingsynchronized external electrical activity with supplemental cardiacdata.

FIG. 5 is an illustrative graphical user interface depicting externalelectrical activity annotated with supplemental cardiac data.

FIG. 6 is a diagram of an illustrative system including an illustrativeimplantable medical device (IMD).

FIG. 7A is a diagram of the illustrative IMD of FIG. 6.

FIG. 7B is a diagram of an enlarged view of a distal end of theelectrical lead disposed in the left ventricle of FIG. 7A.

FIG. 8A is a block diagram of an illustrative IMD, e.g., of the systemsof FIGS. 6-7.

FIG. 8B is another block diagram of an illustrative IMD (e.g., animplantable pulse generator) circuitry and associated leads employed inthe systems of FIGS. 6-7.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In the following detailed description of illustrative embodiments,reference is made to the accompanying figures of the drawing which forma part hereof, and in which are shown, by way of illustration, specificembodiments which may be practiced. It is to be understood that otherembodiments may be utilized and that structural changes may be madewithout departing from (e.g., still falling within) the scope of thedisclosure presented hereby.

Illustrative systems and methods shall be described with reference toFIGS. 1-8. It will be apparent to one skilled in the art that elementsor processes from one embodiment may be used in combination withelements or processes of the other embodiments, and that the possibleembodiments of such systems and methods using combinations of featuresset forth herein is not limited to the specific embodiments shown in theFigures and/or described herein. Further, it will be recognized that theembodiments described herein may include many elements that are notnecessarily shown to scale. Still further, it will be recognized thattiming of the processes and the size and shape of various elementsherein may be modified but still fall within the scope of the presentdisclosure, although certain timings, one or more shapes and/or sizes,or types of elements, may be advantageous over others.

A plurality of electrocardiogram (ECG) signals (e.g., torso-surfacepotentials) may be measured, or monitored, using a plurality of externalelectrodes positioned about the surface, or skin, of a patient. The ECGsignals may be used to evaluate and configure cardiac therapy such as,e.g., cardiac therapy provide by an implantable medical deviceperforming cardiac resynchronization therapy (CRT). As described herein,the ECG signals may be gathered or obtained noninvasively since, e.g.,implantable electrodes may not be used to measure the ECG signals.Further, the ECG signals may be used to determine cardiac electricalactivation times, which may be used to generate various metrics (e.g.,electrical heterogeneity information) that may be used by a user (e.g.,physician) to optimize one or more settings, or parameters, of cardiactherapy (e.g., pacing therapy) such as CRT.

Various illustrative systems, methods, and graphical user interfaces maybe configured to use electrode apparatus including external electrodes,display apparatus, and computing apparatus to noninvasively assist auser (e.g., a physician) in the evaluation of cardiac health and/or theconfiguration (e.g., optimization) of cardiac therapy. An illustrativesystem 100 including electrode apparatus 110, computing apparatus 140,and a remote computing device 160 is depicted in FIG. 1.

The electrode apparatus 110 as shown includes a plurality of electrodesincorporated, or included, within a band wrapped around the chest, ortorso, of a patient 14. The electrode apparatus 110 is operativelycoupled to the computing apparatus 140 (e.g., through one or wiredelectrical connections, wirelessly, etc.) to provide electrical signalsfrom each of the electrodes to the computing apparatus 140 for analysis,evaluation, etc. Illustrative electrode apparatus may be described inU.S. Pat. No. 9,320,446 entitled “Bioelectric Sensor Device and Methods”filed Mar. 27, 2014 and issued on Mar. 26, 2016, which is incorporatedherein by reference in its entirety. Further, illustrative electrodeapparatus 110 will be described in more detail in reference to FIGS.2-3.

Although not described herein, the illustrative system 100 may furtherinclude imaging apparatus. The imaging apparatus may be any type ofimaging apparatus configured to image, or provide images of, at least aportion of the patient in a noninvasive manner. For example, the imagingapparatus may not use any components or parts that may be located withinthe patient to provide images of the patient except noninvasive toolssuch as contrast solution. It is to be understood that the illustrativesystems, methods, and interfaces described herein may further useimaging apparatus to provide noninvasive assistance to a user (e.g., aphysician) to locate, or place, one or more pacing electrodes proximatethe patient's heart in conjunction with the configuration of cardiactherapy.

For example, the illustrative systems and methods may provide imageguided navigation that may be used to navigate leads includingelectrodes, leadless electrodes, wireless electrodes, catheters, etc.,within the patient's body while also providing noninvasive cardiactherapy configuration including determining an effective, or optimal,pre-excitation intervals such as A-V and V-V intervals, etc.Illustrative systems and methods that use imaging apparatus and/orelectrode apparatus may be described in U.S. Pat. App. Pub. No.2014/0371832 to Ghosh published on Dec. 18, 2014, U.S. Pat. App. Pub.No. 2014/0371833 to Ghosh et al. published on Dec. 18, 2014, U.S. Pat.App. Pub. No. 2014/0323892 to Ghosh et al. published on Oct. 30, 2014,U.S. Pat. App. Pub. No. 2014/0323882 to Ghosh et al. published on Oct.20, 2014, each of which is incorporated herein by reference in itsentirety.

Illustrative imaging apparatus may be configured to capture x-ray imagesand/or any other alternative imaging modality. For example, the imagingapparatus may be configured to capture images, or image data, usingisocentric fluoroscopy, bi-plane fluoroscopy, ultrasound, computedtomography (CT), multi-slice computed tomography (MSCT), magneticresonance imaging (MRI), high frequency ultrasound (HIFU), opticalcoherence tomography (OCT), intra-vascular ultrasound (IVUS), twodimensional (2D) ultrasound, three dimensional (3D) ultrasound, fourdimensional (4D) ultrasound, intraoperative CT, intraoperative MRI, etc.Further, it is to be understood that the imaging apparatus may beconfigured to capture a plurality of consecutive images (e.g.,continuously) to provide video frame data. In other words, a pluralityof images taken over time using the imaging apparatus may provide videoframe, or motion picture, data. Additionally, the images may also beobtained and displayed in two, three, or four dimensions. In moreadvanced forms, four-dimensional surface rendering of the heart or otherregions of the body may also be achieved by incorporating heart data orother soft tissue data from a map or from pre-operative image datacaptured by MRI, CT, or echocardiography modalities. Image datasets fromhybrid modalities, such as positron emission tomography (PET) combinedwith CT, or single photon emission computer tomography (SPECT) combinedwith CT, could also provide functional image data superimposed ontoanatomical data, e.g., to be used to navigate implantable apparatus totarget locations within the heart or other areas of interest.

Systems and/or imaging apparatus that may be used in conjunction withthe illustrative systems and method described herein are described inU.S. Pat. App. Pub. No. 2005/0008210 to Evron et al. published on Jan.13, 2005, U.S. Pat. App. Pub. No. 2006/0074285 to Zarkh et al. publishedon Apr. 6, 2006, U.S. Pat. No. 8,731,642 to Zarkh et al. issued on May20, 2014, U.S. Pat. No. 8,861,830 to Brada et al. issued on Oct. 14,2014, U.S. Pat. No. 6,980,675 to Evron et al. issued on Dec. 27, 2005,U.S. Pat. No. 7,286,866 to Okerlund et al. issued on Oct. 23, 2007, U.S.Pat. No. 7,308,297 to Reddy et al. issued on Dec. 11, 2011, U.S. Pat.No. 7,308,299 to Burrell et al. issued on Dec. 11, 2011, U.S. Pat. No.7,321,677 to Evron et al. issued on Jan. 22, 2008, U.S. Pat. No.7,346,381 to Okerlund et al. issued on Mar. 18, 2008, U.S. Pat. No.7,454,248 to Burrell et al. issued on Nov. 18, 2008, U.S. Pat. No.7,499,743 to Vass et al. issued on Mar. 3, 2009, U.S. Pat. No. 7,565,190to Okerlund et al. issued on Jul. 21, 2009, U.S. Pat. No. 7,587,074 toZarkh et al. issued on Sep. 8, 2009, U.S. Pat. No. 7,599,730 to Hunteret al. issued on Oct. 6, 2009, U.S. Pat. No. 7,613,500 to Vass et al.issued on Nov. 3, 2009, U.S. Pat. No. 7,742,629 to Zarkh et al. issuedon Jun. 22, 2010, U.S. Pat. No. 7,747,047 to Okerlund et al. issued onJun. 29, 2010, U.S. Pat. No. 7,778,685 to Evron et al. issued on Aug.17, 2010, U.S. Pat. No. 7,778,686 to Vass et al. issued on Aug. 17,2010, U.S. Pat. No. 7,813,785 to Okerlund et al. issued on Oct. 12,2010, U.S. Pat. No. 7,996,063 to Vass et al. issued on Aug. 9, 2011,U.S. Pat. No. 8,060,185 to Hunter et al. issued on Nov. 15, 2011, andU.S. Pat. No. 8,401,616 to Verard et al. issued on Mar. 19, 2013, eachof which is incorporated herein by reference in its entirety.

The computing apparatus 140 and the remote computing device 160 may eachinclude display apparatus 130, 160, respectively, that may be configuredto display and analyze data such as, e.g., electrical signals (e.g.,electrocardiogram data), electrical activation times, electricalheterogeneity information, etc. For example, one cardiac cycle, or oneheartbeat, of a plurality of cardiac cycles, or heartbeats, representedby the electrical signals collected or monitored by the electrodeapparatus 110 may be analyzed and evaluated for one or more metricsincluding activation times and electrical heterogeneity information thatmay be pertinent to the therapeutic nature of one or more parametersrelated to cardiac therapy such as, e.g., pacing parameters, leadlocation, etc. More specifically, for example, the QRS complex of asingle cardiac cycle may be evaluated for one or more metrics such as,e.g., QRS onset, QRS offset, QRS peak, electrical heterogeneityinformation (EHI), electrical activation times referenced to theearliest activation time, left ventricular or thoracic standarddeviation of electrical activation times (LVED), standard deviation ofactivation times (SDAT), average left ventricular or thoracic surrogateelectrical activation times (LVAT), QRS duration (e.g., interval betweenQRS onset to QRS offset), difference between average left surrogate andaverage right surrogate activation times, relative or absolute QRSmorphology, difference between a higher percentile and a lowerpercentile of activation times (higher percentile may be 90%, 80%, 75%,70%, etc. and lower percentile may be 10%, 15%, 20%, 25% and 30%, etc.),other statistical measures of central tendency (e.g., median or mode),dispersion (e.g., mean deviation, standard deviation, variance,interquartile deviations, range), etc. Further, each of the one or moremetrics may be location specific. For example, some metrics may becomputed from signals recorded, or monitored, from electrodes positionedabout a selected area of the patient such as, e.g., the left side of thepatient, the right side of the patient, etc.

In at least one embodiment, one or both of the computing apparatus 140and the remote computing device 160 may be a server, a personalcomputer, or a tablet computer. The computing apparatus 140 may beconfigured to receive input from input apparatus 142 (e.g., a keyboard)and transmit output to the display apparatus 130, and the remotecomputing device 160 may be configured to receive input from inputapparatus 162 (e.g., a touchscreen) and transmit output to the displayapparatus 170. One or both of the computing apparatus 140 and the remotecomputing device 160 may include data storage that may allow for accessto processing programs or routines and/or one or more other types ofdata, e.g., for analyzing a plurality of electrical signals captured bythe electrode apparatus 110, for determining QRS onsets, QRS offsets,medians, modes, averages, peaks or maximum values, valleys or minimumvalues, for determining electrical activation times, for driving agraphical user interface configured to noninvasively assist a user inconfiguring one or more pacing parameters, or settings, such as, e.g.,pacing rate, ventricular pacing rate, A-V interval, V-V interval, pacingpulse width, pacing vector, multipoint pacing vector (e.g., leftventricular vector quad lead), pacing voltage, pacing configuration(e.g., biventricular pacing, right ventricle only pacing, left ventricleonly pacing, etc.), and arrhythmia detection and treatment, rateadaptive settings and performance, etc.

The computing apparatus 140 may be operatively coupled to the inputapparatus 142 and the display apparatus 130 to, e.g., transmit data toand from each of the input apparatus 142 and the display apparatus 130,and the remote computing device 160 may be operatively coupled to theinput apparatus 162 and the display apparatus 170 to, e.g., transmitdata to and from each of the input apparatus 162 and the displayapparatus 170. For example, the computing apparatus 140 and the remotecomputing device 160 may be electrically coupled to the input apparatus142, 162 and the display apparatus 130, 170 using, e.g., analogelectrical connections, digital electrical connections, wirelessconnections, bus-based connections, network-based connections,internet-based connections, etc. As described further herein, a user mayprovide input to the input apparatus 142, 162 to view and/or select oneor more pieces of configuration information related to the cardiactherapy delivered by cardiac therapy apparatus such as, e.g., animplantable medical device.

Each of the remote computing apparatus 160 and computing device 140 mayinclude a communication interface. The communication interfaces of theremote computing apparatus 160 and the computing device 140 may be usedto communicate with other devices and apparatus such as the electrodeapparatus 110 and each other. As will be described further herein, thecommunication interfaces may be used to acquire supplemental cardiacdata from a plurality of different implanted or external medicaldevices. In one embodiment, the communication interfaces may include atransceiver and antenna for wirelessly communicating with an externaldevice using radio frequency (RF) communication or other communicationprotocols. Further, the communication interfaces may be configured to beunidirectional or bi-directional.

Although as depicted the input apparatus 142 is a keyboard and the inputapparatus 162 is a touchscreen, it is to be understood that the inputapparatus 142, 162 may include any apparatus capable of providing inputto the computing apparatus 140 and the computing device 160 to performthe functionality, methods, and/or logic described herein. For example,the input apparatus 142, 162 may include a keyboard, a mouse, atrackball, a touchscreen (e.g., capacitive touchscreen, a resistivetouchscreen, a multi-touch touchscreen, etc.), etc. Likewise, thedisplay apparatus 130, 170 may include any apparatus capable ofdisplaying information to a user, such as a graphical user interface132, 172 including electrode status information, graphical maps ofelectrical activation, a plurality of signals for the externalelectrodes over one or more heartbeats, QRS complexes, various cardiactherapy scenario selection regions, various rankings of cardiac therapyscenarios, various pacing parameters, electrical heterogeneityinformation (EHI), textual instructions, graphical depictions of anatomyof a human heart, images or graphical depictions of the patient's heart,graphical depictions of locations of one or more electrodes, graphicaldepictions of a human torso, images or graphical depictions of thepatient's torso, graphical depictions or actual images of implantedelectrodes and/or leads, etc. Further, the display apparatus 130, 170may include a liquid crystal display, an organic light-emitting diodescreen, a touchscreen, a cathode ray tube display, etc.

The processing programs or routines stored and/or executed by thecomputing apparatus 140 and the remote computing device 160 may includeprograms or routines for computational mathematics, matrix mathematics,decomposition algorithms, compression algorithms (e.g., data compressionalgorithms), calibration algorithms, image construction algorithms,signal processing algorithms (e.g., various filtering algorithms,Fourier transforms, fast Fourier transforms, etc.), standardizationalgorithms, comparison algorithms, vector mathematics, or any otherprocessing used to implement one or more illustrative methods and/orprocesses described herein. Data stored and/or used by the computingapparatus 140 and the remote computing device 160 may include, forexample, electrical signal/waveform data from the electrode apparatus110 (e.g., a plurality of QRS complexes), electrical activation timesfrom the electrode apparatus 110, cardiac sound/signal/waveform datafrom acoustic sensors, graphics (e.g., graphical elements, icons,buttons, windows, dialogs, pull-down menus, graphic areas, graphicregions, 3D graphics, etc.), graphical user interfaces, results from oneor more processing programs or routines employed according to thedisclosure herein (e.g., electrical signals, electrical heterogeneityinformation, etc.), or any other data that may be used for carrying outthe one and/or more processes or methods described herein.

In one or more embodiments, the illustrative systems, methods, andinterfaces may be implemented using one or more computer programsexecuted on programmable computers, such as computers that include, forexample, processing capabilities, data storage (e.g., volatile ornon-volatile memory and/or storage elements), input devices, and outputdevices. Program code and/or logic described herein may be applied toinput data to perform functionality described herein and generatedesired output information. The output information may be applied asinput to one or more other devices and/or methods as described herein oras would be applied in a known fashion.

The one or more programs used to implement the systems, methods, and/orinterfaces described herein may be provided using any programmablelanguage, e.g., a high-level procedural and/or object orientatedprogramming language that is suitable for communicating with a computersystem. Any such programs may, for example, be stored on any suitabledevice, e.g., a storage media, that is readable by a general or specialpurpose program running on a computer system (e.g., including processingapparatus) for configuring and operating the computer system when thesuitable device is read for performing the procedures described herein.In other words, at least in one embodiment, the illustrative systems,methods, and interfaces may be implemented using a computer readablestorage medium, configured with a computer program, where the storagemedium so configured causes the computer to operate in a specific andpredefined manner to perform functions described herein. Further, in atleast one embodiment, the illustrative systems, methods, and interfacesmay be described as being implemented by logic (e.g., object code)encoded in one or more non-transitory media that includes code forexecution and, when executed by a processor or processing circuitry, isoperable to perform operations such as the methods, processes, and/orfunctionality described herein.

The computing apparatus 140 and the remote computing device 160 may be,for example, any fixed or mobile computer system (e.g., a controller, amicrocontroller, a personal computer, minicomputer, tablet computer,etc.). The exact configurations of the computing apparatus 140 and theremote computing device 160 are not limiting, and essentially any devicecapable of providing suitable computing capabilities and controlcapabilities (e.g., signal analysis, mathematical functions such asmedians, modes, averages, maximum value determination, minimum valuedetermination, slope determination, minimum slope determination, maximumslope determination, graphics processing, etc.) may be used. Asdescribed herein, a digital file may be any medium (e.g., volatile ornon-volatile memory, a CD-ROM, a punch card, magnetic recordable tape,etc.) containing digital bits (e.g., encoded in binary, trinary, etc.)that may be readable and/or writeable by the computing apparatus 140 andthe remote computing device 160 described herein. Also, as describedherein, a file in user-readable format may be any representation of data(e.g., ASCII text, binary numbers, hexadecimal numbers, decimal numbers,graphically, etc.) presentable on any medium (e.g., paper, a display,etc.) readable and/or understandable by a user. Each of the remotecomputing apparatus 140 and local computing device may include acommunication interface. The communication interface of the remotecomputing apparatus 140 may be referred to as the remote communicationinterface, and the communication interface of the local computing device160 may be referred to as the local communication interface. Thecommunication interfaces of the remote computing apparatus 160 and thecomputing device 140 may be used to communicate with other devices andapparatus such as the electrode apparatus 110, any other medical devicethat may include supplemental cardiac data, and each other. In oneembodiment, the communication interfaces may include a transceiver andantenna for wirelessly communicating with an external device using radiofrequency (RF) communication or other communication protocols. Further,the communication interfaces may be configured to be unidirectional orbi-directional.

In view of the above, it will be readily apparent that the functionalityas described in one or more embodiments according to the presentdisclosure may be implemented in any manner as would be known to oneskilled in the art. As such, the computer language, the computer system,or any other software/hardware which is to be used to implement theprocesses described herein shall not be limiting on the scope of thesystems, processes, or programs (e.g., the functionality provided bysuch systems, processes, or programs) described herein.

The illustrative electrode apparatus 110 may be configured to measurebody-surface potentials of a patient 14 and, more particularly,torso-surface potentials of a patient 14. As shown in FIG. 2, theillustrative electrode apparatus 110 may include a set, or array, ofexternal electrodes 112, a strap 113, and interface/amplifier circuitry116. The electrodes 112 may be attached, or coupled, to the strap 113and the strap 113 may be configured to be wrapped around the torso of apatient 14 such that the electrodes 112 surround the patient's heart. Asfurther illustrated, the electrodes 112 may be positioned around thecircumference of a patient 14, including the posterior, lateral,posterolateral, anterolateral, and anterior locations of the torso of apatient 14.

The illustrative electrode apparatus 110 may be further configured tomeasure, or monitor, sounds from at least one or both the patient 14. Asshown in FIG. 2, the illustrative electrode apparatus 110 may include aset, or array, of acoustic sensors 120 attached, or coupled, to thestrap 113. The strap 113 may be configured to be wrapped around thetorso of a patient 14 such that the acoustic sensors 120 surround thepatient's heart. As further illustrated, the acoustic sensors 120 may bepositioned around the circumference of a patient 14, including theposterior, lateral, posterolateral, anterolateral, and anteriorlocations of the torso of a patient 14.

Further, the electrodes 112 and the acoustic sensors 120 may beelectrically connected to interface/amplifier circuitry 116 via wiredconnection 118. The interface/amplifier circuitry 116 may be configuredto amplify the signals from the electrodes 112 and the acoustic sensors120 and provide the signals to one or both of the computing apparatus140 and the remote computing device 160. Other illustrative systems mayuse a wireless connection to transmit the signals sensed by electrodes112 and the acoustic sensors 120 to the interface/amplifier circuitry116 and, in turn, to one or both of the computing apparatus 140 and theremote computing device 160, e.g., as channels of data. In one or moreembodiments, the interface/amplifier circuitry 116 may be electricallycoupled to the computing apparatus 140 using, e.g., analog electricalconnections, digital electrical connections, wireless connections,bus-based connections, network-based connections, internet-basedconnections, etc.

Although in the example of FIG. 2 the electrode apparatus 110 includes astrap 113, in other examples any of a variety of mechanisms, e.g., tapeor adhesives, may be employed to aid in the spacing and placement ofelectrodes 112 and the acoustic sensors 120. In some examples, the strap113 may include an elastic band, strip of tape, or cloth. Further, insome examples, the strap 113 may be part of, or integrated with, a pieceof clothing such as, e.g., a t-shirt. In other examples, the electrodes112 and the acoustic sensors 120 may be placed individually on the torsoof a patient 14. Further, in other examples, one or both of theelectrodes 112 (e.g., arranged in an array) and the acoustic sensors 120(e.g., also arranged in an array) may be part of, or located within,patches, vests, and/or other manners of securing the electrodes 112 andthe acoustic sensors 120 to the torso of the patient 14. Still further,in other examples, one or both of the electrodes 112 and the acousticsensors 120 may be part of, or located within, two sections of materialor two patches. One of the two patches may be located on the anteriorside of the torso of the patient 14 (to, e.g., monitor electricalsignals representative of the anterior side of the patient's heart,measure surrogate cardiac electrical activation times representative ofthe anterior side of the patient's heart, monitor or measure sounds ofthe anterior side of the patient, etc.) and the other patch may belocated on the posterior side of the torso of the patient 14 (to, e.g.,monitor electrical signals representative of the posterior side of thepatient's heart, measure surrogate cardiac electrical activation timesrepresentative of the posterior side of the patient's heart, monitor ormeasure sounds of the posterior side of the patient, etc.). And stillfurther, in other examples, one or both of the electrodes 112 and theacoustic sensors 120 may be arranged in a top row and bottom row thatextend from the anterior side of the patient 14 across the left side ofthe patient 14 to the posterior side of the patient 14. Yet stillfurther, in other examples, one or both of the electrodes 112 and theacoustic sensors 120 may be arranged in a curve around the armpit areaand may have an electrode/sensor-density that less dense on the rightthorax that the other remaining areas.

The electrodes 112 may be configured to surround the heart of thepatient 14 and record, or monitor, the electrical signals associatedwith the depolarization and repolarization of the heart after thesignals have propagated through the torso of a patient 14. Each of theelectrodes 112 may be used in a unipolar configuration to sense thetorso-surface potentials that reflect the cardiac signals. Theinterface/amplifier circuitry 116 may also be coupled to a return orindifferent electrode (not shown) that may be used in combination witheach electrode 112 for unipolar sensing.

In some examples, there may be about 12 to about 50 electrodes 112 andabout 12 to about 50 acoustic sensors 120 spatially distributed aroundthe torso of a patient. Other configurations may have more or fewerelectrodes 112 and more or fewer acoustic sensors 120. It is to beunderstood that the electrodes 112 and acoustic sensors 120 may not bearranged or distributed in an array extending all the way around orcompletely around the patient 14. Instead, the electrodes 112 andacoustic sensors 120 may be arranged in an array that extends only partof the way or partially around the patient 14. For example, theelectrodes 112 and acoustic sensors 120 may be distributed on theanterior, posterior, and left sides of the patient with less or noelectrodes and acoustic sensors proximate the right side (includingposterior and anterior regions of the right side of the patient).

The computing apparatus 140 may record and analyze the torso-surfacepotential signals sensed by electrodes 112 and the sound signals sensedby the acoustic sensors 120, which are amplified/conditioned by theinterface/amplifier circuitry 116. The computing apparatus 140 may beconfigured to analyze the electrical signals from the electrodes 112 toprovide electrocardiogram (ECG) signals, information, or data from thepatient's heart as will be further described herein. The computingapparatus 140 may be configured to analyze the electrical signals fromthe acoustic sensors 120 to provide sound signals, information, or datafrom the patient's body and/or devices implanted therein (such as a leftventricular assist device).

Additionally, the computing apparatus 140 and the remote computingdevice 160 may be configured to provide graphical user interfaces 132,172 depicting various information related to the electrode apparatus 110and the data gathered, or sensed, using the electrode apparatus 110. Forexample, the graphical user interfaces 132, 172 may depict ECGsincluding QRS complexes obtained using the electrode apparatus 110 andsound data including sound waves obtained using the acoustic sensors 120as well as other information related thereto. Illustrative systems andmethods may noninvasively use the electrical information collected usingthe electrode apparatus 110 and the sound information collected usingthe acoustic sensors 120 to evaluate a patient's cardiac health and toevaluate and configure cardiac therapy being delivered to the patient.

Further, the electrode apparatus 110 may further include referenceelectrodes and/or drive electrodes to be, e.g. positioned about thelower torso of the patient 14, that may be further used by the system100. For example, the electrode apparatus 110 may include threereference electrodes, and the signals from the three referenceelectrodes may be combined to provide a reference signal. Further, theelectrode apparatus 110 may use of three caudal reference electrodes(e.g., instead of standard references used in a Wilson Central Terminal)to get a “true” unipolar signal with less noise from averaging threecaudally located reference signals.

FIG. 3 illustrates another illustrative electrode apparatus 110 thatincludes a plurality of electrodes 112 configured to surround the heartof the patient 14 and record, or monitor, the electrical signalsassociated with the depolarization and repolarization of the heart afterthe signals have propagated through the torso of the patient 14 and aplurality of acoustic sensors 120 configured to surround the heart ofthe patient 14 and record, or monitor, the sound signals associated withthe heart after the signals have propagated through the torso of thepatient 14. The electrode apparatus 110 may include a vest 114 uponwhich the plurality of electrodes 112 and the plurality of acousticsensors 120 may be attached, or to which the electrodes 112 and theacoustic sensors 120 may be coupled. In at least one embodiment, theplurality, or array, of electrodes 112 may be used to collect electricalinformation such as, e.g., surrogate electrical activation times.Similar to the electrode apparatus 110 of FIG. 2, the electrodeapparatus 110 of FIG. 3 may include interface/amplifier circuitry 116electrically coupled to each of the electrodes 112 and the acousticsensors 120 through a wired connection 118 and be configured to transmitsignals from the electrodes 112 and the acoustic sensors 120 tocomputing apparatus 140. As illustrated, the electrodes 112 and theacoustic sensors 120 may be distributed over the torso of a patient 14,including, for example, the posterior, lateral, posterolateral,anterolateral, and anterior locations of the torso of a patient 14.

The vest 114 may be formed of fabric with the electrodes 112 and theacoustic sensors 120 attached to the fabric. The vest 114 may beconfigured to maintain the position and spacing of electrodes 112 andthe acoustic sensors 120 on the torso of the patient 14. Further, thevest 114 may be marked to assist in determining the location of theelectrodes 112 and the acoustic sensors 120 on the surface of the torsoof the patient 14. In some examples, there may be about 25 to about 256electrodes 112 and about 25 to about 256 acoustic sensors 120distributed around the torso of the patient 14, though otherconfigurations may have more or fewer electrodes 112 and more or feweracoustic sensors 120.

Further, it is to be understood that the computing apparatus 140, theremote computing device 160, and any other devices described herein maybe operatively coupled to each other in a plurality of different ways soas to perform, or execute, the functionality described herein. Forexample, in the embodiment depicted, the computing device 140, theremote computing device 160, and another other device or devices thatmay be provide supplemental cardiac data may be wireless operablycoupled to each other as depicted by the wireless signal lines emanatingtherebetween in FIG. 1. Additionally, as opposed to wirelessconnections, one or more of the computing apparatus 140, the remotingcomputing device 160, and other devices providing supplemental cardiacdata may be operably coupled to each other through one or wiredelectrical connections.

The illustrative systems and methods may be used to provide noninvasiveassistance to a user in the evaluation of a patient's cardiac healthand/or evaluation and configuration of cardiac therapy being presentlydelivered to the patient (e.g., by an implantable medical device, by aLVAD, etc.). For example, the illustrative systems and methods may beused to assist a user in the configuration and/or adjustment of one ormore cardiac therapy settings such as, e.g., optimization of the A-Vinterval, or delay, of pacing therapy (e.g., left ventricular-only, orleft univentricular, pacing therapy) and the A-V interval, or delay, andthe V-V interval, or delay, of pacing therapy (e.g., biventricularpacing therapy).

An illustrative method 200 of providing synchronized external electricalactivity with supplemental cardiac data is depicted in FIG. 4. Theillustrative method 200 may be generally described linking electricalactivity monitored by a plurality of external electrodes from the skinof a patient to supplemental cardiac data that is provided by any otherdevice configured to collect cardiac data from the patient.

The illustrative method 200 may include monitoring, or measuring,electrical activity using a plurality of external electrodes 202. Theplurality of external electrodes may be similar to the externalelectrodes provided by the electrode apparatus 110 as described hereinwith respect to FIGS. 1-3. For example, the plurality of externalelectrodes may be part, or incorporated into, a vest or band that islocated about a patient's torso. More specifically, the plurality ofelectrodes may be described as being surface electrodes positioned in anarray configured to be located proximate the skin of the torso of apatient. The electrical activity monitored during process 202 prior tothe delivery of cardiac therapy may be referred to as “baseline”electrical activity because no therapy is delivered to the patient suchthat the patient's heart is in its natural, or intrinsic, rhythm.

The method 200 may further include receiving supplemental cardiac data204. The supplemental cardiac data may include any data other than themonitored electrical activity by the plurality of external electrodesthat is related to the patient's heart. For example, the supplementalcardiac data may include various signals representative of data overtime such as internal cardiac electrical signals (e.g., measured beneaththe patient's skin), cardiac sounds, cardiac pressures, blood flows,estimated instantaneous flow waveforms provided by a left ventricularassist device, etc.

Further, for example, the supplemental cardiac data may include variousmarkers indicative of occurrence of cardiac events. More specifically,such markers may include markers indicative an intrinsic atrialdepolarization, atrial pace, a premature atrial complex, an intrinsicventricular depolarization, ventricular pace, a premature ventricularcomplex, ventricular repolarization during an intrinsic or pacedventricular event, effective ventricular or atrial capture, ineffectiveventricular or atrial capture, heart valve closure, heart valve opening,systole, and diastole.

The supplemental cardiac data may be acquired from a plurality ofdifferent implanted or external sources. For example, the supplementalcardiac data may be acquired from an implantable medical device.Further, for example, the supplemental cardiac data may be acquired froman external array of acoustic sensors such as shown herein with respectto the electrode apparatus 110 of FIGS. 1-3. Still further, for example,the supplemental cardiac data may be acquired the from a cardiac pacingdevice, a left ventricular assist device, cardioverter-defibrillator, asubcutaneous monitoring device, and an intracardiac pressure sensor.

Once electrical activity has been monitored 202 and the supplementalcardiac data has been received 204, the method 200 may includesynchronizing the monitored electrical activity and the supplementalcardiac data 206. For example, each of the monitored electrical activityand the supplemental cardiac data may have time information (e.g., timestamps) related thereto. In other words, when the monitored electricalactivity and the supplemental cardiac data are collected, a clock may“keep track” of the data with respect to time. The time information ofthe monitored electrical activity and the time information of thesupplemental cardiac data may be linked so as to synchronize themonitored electrical activity and the supplemental cardiac data.Further, for example, each of the electrode apparatus/computingapparatus and the device providing the supplemental cardiac data mayinclude clocks that will be synchronized so that when the device sendsthe marker information along with the clock-cycle or time-stampsmeasured by the implantable device, the electrode apparatus/computingapparatus can receive and place the marker signal in proper timing withrespect to its own clock and own data. Still further, for example,synchronization between the electrode apparatus/computing apparatus andthe device providing supplemental cardiac data may be performed bymatching the clock-time of apparatus and device to each other orcalibrating them to a time server. In at least one embodiment, suchsynchronization may be performed via cloud-based technologies.

After the monitored electrical activity and the supplemental cardiacdata has been synchronized, or linked, the method 200 may utilize suchsynchronized, or linked, to perform various processes to enhance themonitored electrical activity, to display the synchronized cardiac data,and generate one or more metrics with respect to the synchronizedcardiac data.

For example, the method 200 may include modifying monitored electricalactivity based on synchronized supplemental cardiac data 208. Forinstance, the monitored electrical activity using the plurality ofexternal electrodes may be used for further analysis. However, themonitored electrical activity may be negatively affected by variouscardiac events such as, e.g., pacing pulses from an implantablepacemaker. As such, in one or more embodiments, monitored electricalactivity may be disregarded for a selected period of time following aventricular pace indicated by the supplemental cardiac data. In thisway, the ventricular pace may not negatively affect the monitoredelectrical activity used for analysis. The selected period of time maybetween about 1 milliseconds (ms) and 20 ms. In at least embodiment, theselected period of time is 5 ms. The selected period of time may bereferred to as a blanking period. In other words, the supplementalcardiac data may be used to filter, or “clean up,” the monitoredelectrical activity.

After the monitored electrical activity has been modified, the method200 may further generated electrical heterogeneity information (EHI) 210based on the modified, monitored electrical activity. The EHI may bedescribed as information, or data, representative of at least one ofmechanical cardiac functionality and electrical cardiac functionality.The EHI and other cardiac therapy information may be described in U.S.Provisional Patent Application No. 61/834,133 entitled “METRICS OFELECTRICAL DYSSYNCHRONY AND ELECTRICAL ACTIVATION PATTERNS FROM SURFACEECG ELECTRODES” and filed on Jun. 12, 2013, which is hereby incorporatedby reference it its entirety.

Electrical heterogeneity information (e.g., data) may be defined asinformation indicative of at least one of mechanical synchrony ordyssynchrony of the heart and/or electrical synchrony or dyssynchrony ofthe heart. In other words, electrical heterogeneity information mayrepresent a surrogate of actual mechanical and/or electricalfunctionality of a patient's heart. In at least one embodiment, relativechanges in electrical heterogeneity information (e.g., from baselineheterogeneity information to therapy heterogeneity information, from afirst set of heterogeneity information to a second set of therapyheterogeneity information, etc.) may be used to determine a surrogatevalue representative of the changes in hemodynamic response (e.g., acutechanges in LV pressure gradients). The left ventricular pressure may betypically monitored invasively with a pressure sensor located in theleft ventricular of a patient's heart. As such, the use of electricalheterogeneity information to determine a surrogate value representativeof the left ventricular pressure may avoid invasive monitoring using aleft ventricular pressure sensor.

In at least one embodiment, the electrical heterogeneity information mayinclude a standard deviation of ventricular activation times measuredusing some or all of the external electrodes, e.g., of the electrodeapparatus 110. Further, local, or regional, electrical heterogeneityinformation may include standard deviations and/or averages ofactivation times measured using electrodes located in certain anatomicareas of the torso. For example, external electrodes on the left side ofthe torso of a patient may be used to compute local, or regional, leftelectrical heterogeneity information.

The electrical heterogeneity information may be generated using one ormore various systems and/or methods. For example, electricalheterogeneity information may be generated using an array, or aplurality, of surface electrodes and/or imaging systems as described inU.S. Pat. App. Pub. No. 2012/0283587 A1 published Nov. 8, 2012 andentitled “ASSESSING INRA-CARDIAC ACTIVATION PATTERNS AND ELECTRICALDYSSYNCHRONY,” U.S. Pat. App. Pub. No. 2012/0284003 A1 published Nov. 8,2012 and entitled “ASSESSING INTRA-CARDIAC ACTIVATION PATTERNS”, andU.S. Pat. No. 8,180,428 B2 issued May 15, 2012 and entitled “METHODS ANDSYSTEMS FOR USE IN SELECTING CARDIAC PACING SITES,” each of which isincorporated herein by reference in its entirety.

Electrical heterogeneity information may include one or more metrics orindices. For example, one of the metrics, or indices, of electricalheterogeneity may be a standard deviation of activation times (SDAT)measured using some or all of the electrodes on the surface of the torsoof a patient. In some examples, the SDAT may be calculated using theestimated cardiac activation times over the surface of a model heart.

Another metric, or index, of electrical heterogeneity may be a leftstandard deviation of surrogate electrical activation times (LVED)monitored by external electrodes located proximate the left side of apatient. Further, another metric, or index, of electrical heterogeneitymay include an average of surrogate electrical activation times (LVAT)monitored by external electrodes located proximate the left side of apatient. The LVED and LVAT may be determined (e.g., calculated,computed, etc.) from electrical activity measured only by electrodesproximate the left side of the patient, which may be referred to as“left” electrodes. The left electrodes may be defined as any surfaceelectrodes located proximate the left ventricle, which includes regionto left of the patient's sternum and spine. In one embodiment, the leftelectrodes may include all anterior electrodes on the left of thesternum and all posterior electrodes to the left of the spine. Inanother embodiment, the left electrodes may include all anteriorelectrodes on the left of the sternum and all posterior electrodes. Inyet another embodiment, the left electrodes may be designated based onthe contour of the left and right sides of the heart as determined usingimaging apparatus (e.g., x-ray, fluoroscopy, etc.).

Another illustrative metric, or index, of dyssynchrony may be a range ofactivation times (RAT) that may be computed as the difference betweenthe maximum and the minimum torso-surface or cardiac activation times,e.g., overall, or for a region. The RAT reflects the span of activationtimes while the SDAT gives an estimate of the dispersion of theactivation times from a mean. The SDAT also provides an estimate of theheterogeneity of the activation times, because if activation times arespatially heterogeneous, the individual activation times will be furtheraway from the mean activation time, indicating that one or more regionsof heart have been delayed in activation. In some examples, the RAT maybe calculated using the estimated cardiac activation times over thesurface of a model heart.

Another illustrative metric, or index, of electrical heterogeneityinformation may include estimates of a percentage of surface electrodeslocated within a particular region of interest for the torso or heartwhose associated activation times are greater than a certain percentile,such as, for example the 70th percentile, of measured QRS complexduration or the determined activation times for surface electrodes. Theregion of interest may, e.g., be a posterior, left anterior, and/orleft-ventricular region. The illustrative metric, or index, may bereferred to as a percentage of late activation (PLAT). The PLAT may bedescribed as providing an estimate of percentage of the region ofinterest, e.g., posterior and left-anterior area associated with theleft ventricular area of heart, which activates late. A large value forPLAT may imply delayed activation of a substantial portion of theregion, e.g., the left ventricle, and the potential benefit ofelectrical resynchronization through CRT by pre-exciting the lateregion, e.g., of left ventricle. In other examples, the PLAT may bedetermined for other subsets of electrodes in other regions, such as aright anterior region to evaluate delayed activation in the rightventricle. Furthermore, in some examples, the PLAT may be calculatedusing the estimated cardiac activation times over the surface of a modelheart for either the whole heart or for a particular region, e.g., leftor right ventricle, of the heart.

In one or more embodiments, the electrical heterogeneity information mayinclude indicators of favorable changes in global cardiac electricalactivation such as, e.g., described in Sweeney et al., “Analysis ofVentricular Activation Using Surface Electrocardiography to Predict LeftVentricular Reverse Volumetric Remodeling During CardiacResynchronization Therapy,” Circulation, 2010 Feb. 9, 121(5): 626-34and/or Van Deursen, et al., “Vectorcardiography as a Tool for EasyOptimization of Cardiac Resynchronization Therapy in Canine LBBBHearts,” Circulation Arrhythmia and Electrophysiology, 2012 Jun. 1,5(3): 544-52, each of which is incorporated herein by reference in itsentirety. Heterogeneity information may also include measurements ofimproved cardiac mechanical function measured by imaging or othersystems to track motion of implanted leads within the heart as, e.g.,described in Ryu et al., “Simultaneous Electrical and Mechanical MappingUsing 3D Cardiac Mapping System: Novel Approach for Optimal CardiacResynchronization Therapy,” Journal of Cardiovascular Electrophysiology,2010 Feb., 21(2): 219-22, Sperzel et al., “IntraoperativeCharacterization of Interventricular Mechanical Dyssynchrony UsingElectroanatomic Mapping System—A Feasibility Study,” Journal ofInterventional Cardiac Electrophysiology, 2012 Nov., 35(2): 189-96,and/or U.S. Pat. App. Pub. No. 2009/0099619 A1 entitled “METHOD FOROPTIMIZAING CRT THERAPY” and published on Apr. 16, 2009, each of whichis incorporated herein by reference in its entirety.

Further, the method 200 may include displaying monitored electricalactivity 212 and annotating the displayed monitored electrical activitywith the synchronized supplemental cardiac data 214. An illustrativegraphical user interface 250 depicting monitored external electricalactivity 260 annotated with supplemental cardiac data are shown in FIG.5.

The graphical user interface 250 of FIG. 5 depicts a plurality ofexternal electrical signals 260 plotted over 5 heart beats or cardiaccycles. A variety of markers from the supplemental cardiac data areannotated about the electrical signals. For example, paced atrialmarkers 270 (one of which is labeled) indicative of when atrial pacesoccurred are represented by solid diamonds. Further, for example,ventricular capture indicators 272 (one of which is labeled) are locatedproximate the electrical signals 260 proximate each cardiac cycleindicating either effective ventricular capture with the letter “E” in asquare or ineffective ventricular capture with the letter “I” in asquare. Still further, for example, paced ventricle markers 274 (one ofwhich is labeled) indicative of when left ventricular paces occurred arerepresented by solid squares. And still further, for example, QRS onsetand QRS offset indicators 276 (one of which is labeled) indicative ofwhen QRS onset and offset are represented by solid vertical lines.

Although only a few pieces of supplemental cardiac data are annotated onthe monitored electrical activity on the graphical user interface 250shown in FIG. 5, it is be understood that any of the supplementalcardiac described herein may be annotated, or added, to the monitoredelectrical activity on the graphical user interface 250. Additionally,the illustrative systems and methods described herein may also allowusers to manually annotate the monitored electrical activity and anyother supplemental cardiac data on the graphical user interface. Forexample, a user may manually annotate ventricular events on themonitored electrical activity. Further, the illustrative systems andmethods may allow configuring various cardiac therapy devices parametersbased, at least in part, on the displayed monitored electrical activity,generated EHI, and supplemental cardiac data. In other words, all thetracings and annotations depicted on the graphical user interface may beevaluated to make decisions about final device parameters.

The method 200 may further include generating one or more metrics 216using data from both of the monitored electrical activity and thesupplemental cardiac data. For example, at least one interval between afirst event indicated by the monitored electrical activity and a secondevent indicated by the supplemental cardiac data may be generated.Examples of such intervals may be cross-chamber intervals like intervalsbetween one atrial event and the next ventricular event or intervalsbetween two successive events in the same chamber like, e.g.,atrial-to-atrial intervals or ventricular-to-ventricular intervals whichprovide the lengths of atrial or ventricular cycles.

Illustrative cardiac therapy systems and devices may be furtherdescribed herein with reference to FIGS. 6-8 that may utilizes theillustrative systems, interfaces, methods, and processes describedherein with respect to FIGS. 1-5. For example, the therapy system 10described in FIGS. 6-8 may be configured to provide supplemental cardiacdata to the illustrative systems and methods for use in synchronizationwith monitored electrical activity.

FIG. 6 is a conceptual diagram illustrating an illustrative therapysystem 10 that may be used to deliver pacing therapy to a patient 14.Patient 14 may, but not necessarily, be a human. The therapy system 10may include an implantable medical device 16 (IMD), which may be coupledto leads 18, 20, 22. The IMD 16 may be, e.g., an implantable pacemaker,cardioverter, and/or defibrillator, that delivers, or provides,electrical signals (e.g., paces, etc.) to and/or senses electricalsignals from the heart 12 of the patient 14 via electrodes coupled toone or more of the leads 18, 20, 22.

The leads 18, 20, 22 extend into the heart 12 of the patient 14 to senseelectrical activity of the heart 12 and/or to deliver electricalstimulation to the heart 12. In the example shown in FIG. 6, the rightventricular (RV) lead 18 extends through one or more veins (not shown),the superior vena cava (not shown), and the right atrium 26, and intothe right ventricle 28. The left ventricular (LV) coronary sinus lead 20extends through one or more veins, the vena cava, the right atrium 26,and into the coronary sinus 30 to a region adjacent to the free wall ofthe left ventricle 32 of the heart 12. The right atrial (RA) lead 22extends through one or more veins and the vena cava, and into the rightatrium 26 of the heart 12.

The IMD 16 may sense, among other things, electrical signals attendantto the depolarization and repolarization of the heart 12 via electrodescoupled to at least one of the leads 18, 20, 22. In some examples, theIMD 16 provides pacing therapy (e.g., pacing pulses) to the heart 12based on the electrical signals sensed within the heart 12. The IMD 16may be operable to adjust one or more parameters associated with thepacing therapy such as, e.g., A-V delay and other various timings, pulsewide, amplitude, voltage, burst length, etc. Further, the IMD 16 may beoperable to use various electrode configurations to deliver pacingtherapy, which may be unipolar, bipolar, quadripoloar, or furthermultipolar. For example, a multipolar lead may include severalelectrodes that can be used for delivering pacing therapy. Hence, amultipolar lead system may provide, or offer, multiple electricalvectors to pace from. A pacing vector may include at least one cathode,which may be at least one electrode located on at least one lead, and atleast one anode, which may be at least one electrode located on at leastone lead (e.g., the same lead, or a different lead) and/or on thecasing, or can, of the 1 MB. While improvement in cardiac function as aresult of the pacing therapy may primarily depend on the cathode, theelectrical parameters like impedance, pacing threshold voltage, currentdrain, longevity, etc. may be more dependent on the pacing vector, whichincludes both the cathode and the anode. The IMD 16 may also providedefibrillation therapy and/or cardioversion therapy via electrodeslocated on at least one of the leads 18, 20, 22. Further, the 1 MB 16may detect arrhythmia of the heart 12, such as fibrillation of theventricles 28, 32, and deliver defibrillation therapy to the heart 12 inthe form of electrical pulses. In some examples, 1 MB 16 may beprogrammed to deliver a progression of therapies, e.g., pulses withincreasing energy levels, until a fibrillation of heart 12 is stopped.

FIGS. 7A-7B are conceptual diagrams illustrating the 1 MB 16 and theleads 18, 20, 22 of therapy system 10 of FIG. 6 in more detail. Theleads 18, 20, 22 may be electrically coupled to a therapy deliverymodule (e.g., for delivery of pacing therapy), a sensing module (e.g.,for sensing one or more signals from one or more electrodes), and/or anyother modules of the IMD 16 via a connector block 34. In some examples,the proximal ends of the leads 18, 20, 22 may include electricalcontacts that electrically couple to respective electrical contactswithin the connector block 34 of the IMD 16. In addition, in someexamples, the leads 18, 20, 22 may be mechanically coupled to theconnector block 34 with the aid of set screws, connection pins, oranother suitable mechanical coupling mechanism.

Each of the leads 18, 20, 22 includes an elongated insulative lead body,which may carry a number of conductors (e.g., concentric coiledconductors, straight conductors, etc.) separated from one another byinsulation (e.g., tubular insulative sheaths). In the illustratedexample, bipolar electrodes 40, 42 are located proximate to a distal endof the lead 18. In addition, bipolar electrodes 44, 45, 46, 47 arelocated proximate to a distal end of the lead 20 and bipolar electrodes48, 50 are located proximate to a distal end of the lead 22.

The electrodes 40, 44, 45, 46, 47, 48 may take the form of ringelectrodes, and the electrodes 42, 50 may take the form of extendablehelix tip electrodes mounted retractably within the insulative electrodeheads 52, 54, 56, respectively. Each of the electrodes 40, 42, 44, 45,46, 47, 48, 50 may be electrically coupled to a respective one of theconductors (e.g., coiled and/or straight) within the lead body of itsassociated lead 18, 20, 22, and thereby coupled to a respective one ofthe electrical contacts on the proximal end of the leads 18, 20, 22.

Additionally, electrodes 44, 45, 46 and 47 may have an electrode surfacearea of about 5.3 mm² to about 5.8 mm². Electrodes 44, 45, 46, and 47may also be referred to as LV1, LV2, LV3, and LV4, respectively. The LVelectrodes (i.e., left ventricle electrode 1 (LV1) 44, left ventricleelectrode 2 (LV2) 45, left ventricle electrode 3 (LV3) 46, and leftventricle 4 (LV4) 47 etc.) on the lead 20 can be spaced apart atvariable distances. For example, electrode 44 may be a distance of,e.g., about 21 millimeters (mm), away from electrode 45, electrodes 45and 46 may be spaced a distance of, e.g. about 1.3 mm to about 1.5 mm,away from each other, and electrodes 46 and 47 may be spaced a distanceof, e.g. 20 mm to about 21 mm, away from each other.

The electrodes 40, 42, 44, 45, 46, 47, 48, 50 may further be used tosense electrical signals (e.g., morphological waveforms withinelectrograms (EGM)) attendant to the depolarization and repolarizationof the heart 12. The electrical signals are conducted to the IMD 16 viathe respective leads 18, 20, 22. In some examples, the IMD 16 may alsodeliver pacing pulses via the electrodes 40, 42, 44, 45, 46, 47, 48, 50to cause depolarization of cardiac tissue of the patient's heart 12. Insome examples, as illustrated in FIG. 7A, the IMD 16 includes one ormore housing electrodes, such as housing electrode 58, which may beformed integrally with an outer surface of a housing 60 (e.g.,hermetically-sealed housing) of the IMD 16 or otherwise coupled to thehousing 60. Any of the electrodes 40, 42, 44, 45, 46, 47, 48, 50 may beused for unipolar sensing or pacing in combination with the housingelectrode 58. It is generally understood by those skilled in the artthat other electrodes can also be selected to define, or be used for,pacing and sensing vectors. Further, any of electrodes 40, 42, 44, 45,46, 47, 48, 50, 58, when not being used to deliver pacing therapy, maybe used to sense electrical activity during pacing therapy.

As described in further detail with reference to FIG. 7A, the housing 60may enclose a therapy delivery module that may include a stimulationgenerator for generating cardiac pacing pulses and defibrillation orcardioversion shocks, as well as a sensing module for monitoring theelectrical signals of the patient's heart (e.g., the patient's heartrhythm). The leads 18, 20, 22 may also include elongated electrodes 62,64, 66, respectively, which may take the form of a coil. The IMD 16 maydeliver defibrillation shocks to the heart 12 via any combination of theelongated electrodes 62, 64, 66 and the housing electrode 58. Theelectrodes 58, 62, 64, 66 may also be used to deliver cardioversionpulses to the heart 12. Further, the electrodes 62, 64, 66 may befabricated from any suitable electrically conductive material, such as,but not limited to, platinum, platinum alloy, and/or other materialsknown to be usable in implantable defibrillation electrodes. Sinceelectrodes 62, 64, 66 are not generally configured to deliver pacingtherapy, any of electrodes 62, 64, 66 may be used to sense electricalactivity and may be used in combination with any of electrodes 40, 42,44, 45, 46, 47, 48, 50, 58. In at least one embodiment, the RV elongatedelectrode 62 may be used to sense electrical activity of a patient'sheart during the delivery of pacing therapy (e.g., in combination withthe housing electrode 58, or defibrillation electrode-to-housingelectrode vector).

The configuration of the illustrative therapy system 10 illustrated inFIGS. 6-8 is merely one example. In other examples, the therapy systemmay include epicardial leads and/or patch electrodes instead of or inaddition to the transvenous leads 18, 20, 22 illustrated in FIG. 6.Additionally, in other examples, the therapy system 10 may be implantedin/around the cardiac space without transvenous leads (e.g.,leadless/wireless pacing systems) or with leads implanted (e.g.,implanted transvenously or using approaches) into the left chambers ofthe heart (in addition to or replacing the transvenous leads placed intothe right chambers of the heart as illustrated in FIG. 6). Further, inone or more embodiments, the IMD 16 need not be implanted within thepatient 14. For example, the IMD 16 may deliver various cardiactherapies to the heart 12 via percutaneous leads that extend through theskin of the patient 14 to a variety of positions within or outside ofthe heart 12. In one or more embodiments, the system 10 may utilizewireless pacing (e.g., using energy transmission to the intracardiacpacing component(s) via ultrasound, inductive coupling, RF, etc.) andsensing cardiac activation using electrodes on the can/housing and/or onsubcutaneous leads.

In other examples of therapy systems that provide electrical stimulationtherapy to the heart 12, such therapy systems may include any suitablenumber of leads coupled to the IMD 16, and each of the leads may extendto any location within or proximate to the heart 12. For example, otherexamples of therapy systems may include three transvenous leads locatedas illustrated in FIGS. 6-8. Still further, other therapy systems mayinclude a single lead that extends from the IMD 16 into the right atrium26 or the right ventricle 28, or two leads that extend into a respectiveone of the right atrium 26 and the right ventricle 28.

FIG. 8A is a functional block diagram of one illustrative configurationof the IMD 16. As shown, the IMD 16 may include a control module 81, atherapy delivery module 84 (e.g., which may include a stimulationgenerator), a sensing module 86, and a power source 90.

The control module, or apparatus, 81 may include a processor 80, memory82, and a telemetry module, or apparatus, 88. The memory 82 may includecomputer-readable instructions that, when executed, e.g., by theprocessor 80, cause the IMD 16 and/or the control module 81 to performvarious functions attributed to the IMD 16 and/or the control module 81described herein. Further, the memory 82 may include any volatile,non-volatile, magnetic, optical, and/or electrical media, such as arandom-access memory (RAM), read-only memory (ROM), non-volatile RAM(NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory,and/or any other digital media. An illustrative capture managementmodule may be the left ventricular capture management (LVCM) moduledescribed in U.S. Pat. No. 7,684,863 entitled “LV THRESHOLD MEASUREMENTAND CAPTURE MANAGEMENT” and issued Mar. 23, 2010, which is incorporatedherein by reference in its entirety.

The processor 80 of the control module 81 may include any one or more ofa microprocessor, a controller, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field-programmablegate array (FPGA), and/or equivalent discrete or integrated logiccircuitry. In some examples, the processor 80 may include multiplecomponents, such as any combination of one or more microprocessors, oneor more controllers, one or more DSPs, one or more ASICs, and/or one ormore FPGAs, as well as other discrete or integrated logic circuitry. Thefunctions attributed to the processor 80 herein may be embodied assoftware, firmware, hardware, or any combination thereof.

The control module 81 may control the therapy delivery module 84 todeliver therapy (e.g., electrical stimulation therapy such as pacing) tothe heart 12 according to a selected one or more therapy programs, whichmay be stored in the memory 82. More, specifically, the control module81 (e.g., the processor 80) may control various parameters of theelectrical stimulus delivered by the therapy delivery module 84 such as,e.g., A-V delays, V-V delays, pacing pulses with the amplitudes, pulsewidths, frequency, or electrode polarities, etc., which may be specifiedby one or more selected therapy programs (e.g., A-V and/or V-V delayadjustment programs, pacing therapy programs, pacing recovery programs,capture management programs, etc.). As shown, the therapy deliverymodule 84 is electrically coupled to electrodes 40, 42, 44, 45, 46, 47,48, 50, 58, 62, 64, 66, e.g., via conductors of the respective lead 18,20, 22, or, in the case of housing electrode 58, via an electricalconductor disposed within housing 60 of IMD 16. Therapy delivery module84 may be configured to generate and deliver electrical stimulationtherapy such as pacing therapy to the heart 12 using one or more of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66.

For example, therapy delivery module 84 may deliver pacing stimulus(e.g., pacing pulses) via ring electrodes 40, 44, 45, 46, 47, 48 coupledto leads 18, 20, 22 and/or helical tip electrodes 42, 50 of leads 18,22. Further, for example, therapy delivery module 84 may deliverdefibrillation shocks to heart 12 via at least two of electrodes 58, 62,64, 66. In some examples, therapy delivery module 84 may be configuredto deliver pacing, cardioversion, or defibrillation stimulation in theform of electrical pulses. In other examples, therapy delivery module 84may be configured deliver one or more of these types of stimulation inthe form of other signals, such as sine waves, square waves, and/orother substantially continuous time signals.

The IMD 16 may further include a switch module 85 and the control module81 (e.g., the processor 80) may use the switch module 85 to select,e.g., via a data/address bus, which of the available electrodes are usedto deliver therapy such as pacing pulses for pacing therapy, or which ofthe available electrodes are used for sensing. The switch module 85 mayinclude a switch array, switch matrix, multiplexer, or any other type ofswitching device suitable to selectively couple the sensing module 86and/or the therapy delivery module 84 to one or more selectedelectrodes. More specifically, the therapy delivery module 84 mayinclude a plurality of pacing output circuits. Each pacing outputcircuit of the plurality of pacing output circuits may be selectivelycoupled, e.g., using the switch module 85, to one or more of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 (e.g., a pairof electrodes for delivery of therapy to a bipolar or multipolar pacingvector). In other words, each electrode can be selectively coupled toone of the pacing output circuits of the therapy delivery module usingthe switching module 85.

The sensing module 86 is coupled (e.g., electrically coupled) to sensingapparatus, which may include, among additional sensing apparatus, theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 to monitorelectrical activity of the heart 12, e.g., electrocardiogram(ECG)/electrogram (EGM) signals, etc. The ECG/EGM signals may be used tomeasure or monitor activation times (e.g., ventricular activationstimes, etc.), heart rate (HR), heart rate variability (HRV), heart rateturbulence (HRT), deceleration/acceleration capacity, decelerationsequence incidence, T-wave alternans (TWA), P-wave to P-wave intervals(also referred to as the P-P intervals or A-A intervals), R-wave toR-wave intervals (also referred to as the R-R intervals or V-Vintervals), P-wave to QRS complex intervals (also referred to as the P-Rintervals, A-V intervals, or P-Q intervals), QRS-complex morphology, STsegment (i.e., the segment that connects the QRS complex and theT-wave), T-wave changes, QT intervals, electrical vectors, etc.

The switch module 85 may also be used with the sensing module 86 toselect which of the available electrodes are used, or enabled, to, e.g.,sense electrical activity of the patient's heart (e.g., one or moreelectrical vectors of the patient's heart using any combination of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66). Likewise,the switch module 85 may also be used with the sensing module 86 toselect which of the available electrodes are not to be used (e.g.,disabled) to, e.g., sense electrical activity of the patient's heart(e.g., one or more electrical vectors of the patient's heart using anycombination of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62,64, 66), etc. In some examples, the control module 81 may select theelectrodes that function as sensing electrodes via the switch modulewithin the sensing module 86, e.g., by providing signals via adata/address bus.

In some examples, sensing module 86 includes a channel that includes anamplifier with a relatively wider pass band than the R-wave or P-waveamplifiers. Signals from the selected sensing electrodes may be providedto a multiplexer, and thereafter converted to multi-bit digital signalsby an analog-to-digital converter for storage in memory 82, e.g., as anelectrogram (EGM). In some examples, the storage of such EGMs in memory82 may be under the control of a direct memory access circuit.

In some examples, the control module 81 may operate as aninterrupt-driven device and may be responsive to interrupts from pacertiming and control module, where the interrupts may correspond to theoccurrences of sensed P-waves and R-waves and the generation of cardiacpacing pulses. Any necessary mathematical calculations may be performedby the processor 80 and any updating of the values or intervalscontrolled by the pacer timing and control module may take placefollowing such interrupts. A portion of memory 82 may be configured as aplurality of recirculating buffers, capable of holding one or moreseries of measured intervals, which may be analyzed by, e.g., theprocessor 80 in response to the occurrence of a pace or sense interruptto determine whether the patient's heart 12 is presently exhibitingatrial or ventricular tachyarrhythmia.

The telemetry module 88 of the control module 81 may include anysuitable hardware, firmware, software, or any combination thereof forcommunicating with another device, such as a programmer. For example,under the control of the processor 80, the telemetry module 88 mayreceive downlink telemetry from and send uplink telemetry to aprogrammer with the aid of an antenna, which may be internal and/orexternal. The processor 80 may provide the data to be uplinked to aprogrammer and the control signals for the telemetry circuit within thetelemetry module 88, e.g., via an address/data bus. In some examples,the telemetry module 88 may provide received data to the processor 80via a multiplexer.

The various components of the IMD 16 are further coupled to a powersource 90, which may include a rechargeable or non-rechargeable battery.A non-rechargeable battery may be selected to last for several years,while a rechargeable battery may be inductively charged from an externaldevice, e.g., on a daily or weekly basis.

FIG. 8B is another embodiment of a functional block diagram for IMD 16that depicts bipolar RA lead 22, bipolar RV lead 18, and bipolar LV CSlead 20 without the LA CS pace/sense electrodes and coupled with animplantable pulse generator (IPG) circuit 31 having programmable modesand parameters of a biventricular DDD/R type known in the pacing art. Inturn, the sensor signal processing circuit 91 indirectly couples to thetiming circuit 43 and via data and control bus to microcomputercircuitry 33. The IPG circuit 31 is illustrated in a functional blockdiagram divided generally into a microcomputer circuit 33 and a pacingcircuit 21. The pacing circuit 21 includes the digital controller/timercircuit 43, the output amplifiers circuit 51, the sense amplifierscircuit 55, the RF telemetry transceiver 41, the activity sensor circuit35 as well as a number of other circuits and components described below.

Crystal oscillator circuit 89 provides the basic timing clock for thepacing circuit 21 while battery 29 provides power. Power-on-resetcircuit 87 responds to initial connection of the circuit to the batteryfor defining an initial operating condition and similarly, resets theoperative state of the device in response to detection of a low batterycondition. Reference mode circuit 37 generates stable voltage referenceand currents for the analog circuits within the pacing circuit 21.Analog-to-digital converter (ADC) and multiplexer circuit 39 digitizeanalog signals and voltage to provide, e.g., real time telemetry ofcardiac signals from sense amplifiers 55 for uplink transmission via RFtransmitter and receiver circuit 41. Voltage reference and bias circuit37, ADC and multiplexer 39, power-on-reset circuit 87, and crystaloscillator circuit 89 may correspond to any of those used inillustrative implantable cardiac pacemakers.

If the IPG is programmed to a rate responsive mode, the signals outputby one or more physiologic sensors are employed as a rate controlparameter (RCP) to derive a physiologic escape interval. For example,the escape interval is adjusted proportionally to the patient's activitylevel developed in the patient activity sensor (PAS) circuit 35 in thedepicted, illustrative IPG circuit 31. The patient activity sensor 27 iscoupled to the IPG housing and may take the form of a piezoelectriccrystal transducer. The output signal of the patient activity sensor 27may be processed and used as an RCP. Sensor 27 generates electricalsignals in response to sensed physical activity that are processed byactivity circuit 35 and provided to digital controller/timer circuit 43.Activity circuit 35 and associated sensor 27 may correspond to thecircuitry disclosed in U.S. Pat. No. 5,052,388 entitled “METHOD ANDAPPARATUS FOR IMPLEMENTING ACTIVITY SENSING IN A PULSE GENERATOR” andissued on Oct. 1, 1991 and U.S. Pat. No. 4,428,378 entitled “RATEADAPTIVE PACER” and issued on Jan. 31, 1984, each of which isincorporated herein by reference in its entirety. Similarly, theillustrative systems, apparatus, and methods described herein may bepracticed in conjunction with alternate types of sensors such asoxygenation sensors, pressure sensors, pH sensors, and respirationsensors, for use in providing rate responsive pacing capabilities.Alternately, QT time may be used as a rate indicating parameter, inwhich case no extra sensor is required. Similarly, the illustrativeembodiments described herein may also be practiced in non-rateresponsive pacemakers.

Data transmission to and from the external programmer is accomplished byway of the telemetry antenna 57 and an associated RF transceiver 41,which serves both to demodulate received downlink telemetry and totransmit uplink telemetry. Uplink telemetry capabilities may include theability to transmit stored digital information, e.g., operating modesand parameters, EGM histograms, and other events, as well as real timeEGMs of atrial and/or ventricular electrical activity and marker channelpulses indicating the occurrence of sensed and paced depolarizations inthe atrium and ventricle.

Microcomputer 33 contains a microprocessor 80 and associated systemclock and on-processor RAM and ROM chips 82A and 82B, respectively. Inaddition, microcomputer circuit 33 includes a separate RAM/ROM chip 82Cto provide additional memory capacity. Microprocessor 80 normallyoperates in a reduced power consumption mode and is interrupt driven.Microprocessor 80 is awakened in response to defined interrupt events,which may include A-TRIG, RV-TRIG, LV-TRIG signals generated by timersin digital timer/controller circuit 43 and A-EVENT, RV-EVENT, andLV-EVENT signals generated by sense amplifiers circuit 55, among others.The specific values of the intervals and delays timed out by digitalcontroller/timer circuit 43 are controlled by the microcomputer circuit33 by way of data and control bus from programmed-in parameter valuesand operating modes. In addition, if programmed to operate as a rateresponsive pacemaker, a timed interrupt, e.g., every cycle or every twoseconds, may be provided in order to allow the microprocessor to analyzethe activity sensor data and update the basic A-A, V-A, or V-V escapeinterval, as applicable. In addition, the microprocessor 80 may alsoserve to define variable, operative A-V delay intervals, V-V delayintervals, and the energy delivered to each ventricle and/or atrium.

In one embodiment, microprocessor 80 is a custom microprocessor adaptedto fetch and execute instructions stored in RAM/ROM unit 82 in aconventional manner. It is contemplated, however, that otherimplementations may be suitable to practice the present disclosure. Forexample, an off-the-shelf, commercially available microprocessor ormicrocontroller, or custom application-specific, hardwired logic, orstate-machine type circuit may perform the functions of microprocessor80.

Digital controller/timer circuit 43 operates under the general controlof the microcomputer 33 to control timing and other functions within thepacing circuit 21 and includes a set of timing and associated logiccircuits of which certain ones pertinent to the present disclosure aredepicted. The depicted timing circuits include URI/LRI timers 83A, V-Vdelay timer 83B, intrinsic interval timers 83C for timing elapsedV-EVENT to V-EVENT intervals or V-EVENT to A-EVENT intervals or the V-Vconduction interval, escape interval timers 83D for timing A-A, V-A,and/or V-V pacing escape intervals, an A-V delay interval timer 83E fortiming the A-LVp delay (or A-RVp delay) from a preceding A-EVENT orA-TRIG, a post-ventricular timer 83F for timing post-ventricular timeperiods, and a date/time clock 83G.

The A-V delay interval timer 83E is loaded with an appropriate delayinterval for one ventricular chamber (e.g., either an A-RVp delay or anA-LVp) to time-out starting from a preceding A-PACE or A-EVENT. Theinterval timer 83E triggers pacing stimulus delivery and can be based onone or more prior cardiac cycles (or from a data set empirically derivedfor a given patient).

The post-event timer 83F times out the post-ventricular time periodfollowing an RV-EVENT or LV-EVENT or a RV-TRIG or LV-TRIG andpost-atrial time periods following an A-EVENT or A-TRIG. The durationsof the post-event time periods may also be selected as programmableparameters stored in the microcomputer 33. The post-ventricular timeperiods include the PVARP, a post-atrial ventricular blanking period(PAVBP), a ventricular blanking period (VBP), a post-ventricular atrialblanking period (PVARP) and a ventricular refractory period (VRP)although other periods can be suitably defined depending, at least inpart, on the operative circuitry employed in the pacing engine. Thepost-atrial time periods include an atrial refractory period (ARP)during which an A-EVENT is ignored for the purpose of resetting any A-Vdelay, and an atrial blanking period (ABP) during which atrial sensingis disabled. It should be noted that the starting of the post-atrialtime periods and the A-V delays can be commenced substantiallysimultaneously with the start or end of each A-EVENT or A-TRIG or, inthe latter case, upon the end of the A-PACE which may follow the A-TRIG.Similarly, the starting of the post-ventricular time periods and the V-Aescape interval can be commenced substantially simultaneously with thestart or end of the V-EVENT or V-TRIG or, in the latter case, upon theend of the V-PACE which may follow the V-TRIG. The microprocessor 80also optionally calculates A-V delays, V-V delays, post-ventricular timeperiods, and post-atrial time periods that vary with the sensor-basedescape interval established in response to the RCP(s) and/or with theintrinsic atrial and/or ventricular rate.

The output amplifiers circuit 51 contains a RA pace pulse generator (anda LA pace pulse generator if LA pacing is provided), a RV pace pulsegenerator, a LV pace pulse generator, and/or any other pulse generatorconfigured to provide atrial and ventricular pacing. In order to triggergeneration of an RV-PACE or LV-PACE pulse, digital controller/timercircuit 43 generates the RV-TRIG signal at the time-out of the A-RVpdelay (in the case of RV pre-excitation) or the LV-TRIG at the time-outof the A-LVp delay (in the case of LV pre-excitation) provided by A-Vdelay interval timer 83E (or the V-V delay timer 83B). Similarly,digital controller/timer circuit 43 generates an RA-TRIG signal thattriggers output of an RA-PACE pulse (or an LA-TRIG signal that triggersoutput of an LA-PACE pulse, if provided) at the end of the V-A escapeinterval timed by escape interval timers 83D.

The output amplifiers circuit 51 includes switching circuits forcoupling selected pace electrode pairs from among the lead conductorsand the IND-CAN electrode 20 to the RA pace pulse generator (and LA pacepulse generator if provided), RV pace pulse generator and LV pace pulsegenerator. Pace/sense electrode pair selection and control circuit 53selects lead conductors and associated pace electrode pairs to becoupled with the atrial and ventricular output amplifiers within outputamplifiers circuit 51 for accomplishing RA, LA, RV and LV pacing.

The sense amplifiers circuit 55 contains sense amplifiers for atrial andventricular pacing and sensing. High impedance P-wave and R-wave senseamplifiers may be used to amplify a voltage difference signal that isgenerated across the sense electrode pairs by the passage of cardiacdepolarization wavefronts. The high impedance sense amplifiers use highgain to amplify the low amplitude signals and rely on pass band filters,time domain filtering and amplitude threshold comparison to discriminatea P-wave or R-wave from background electrical noise. Digitalcontroller/timer circuit 43 controls sensitivity settings of the atrialand ventricular sense amplifiers 55.

The sense amplifiers may be uncoupled from the sense electrodes duringthe blanking periods before, during, and after delivery of a pace pulseto any of the pace electrodes of the pacing system to avoid saturationof the sense amplifiers. The sense amplifiers circuit 55 includesblanking circuits for uncoupling the selected pairs of the leadconductors and the IND-CAN electrode 20 from the inputs of the RA senseamplifier (and LA sense amplifier if provided), RV sense amplifier andLV sense amplifier during the ABP, PVABP and VBP. The sense amplifierscircuit 55 also includes switching circuits for coupling selected senseelectrode lead conductors and the IND-CAN electrode 20 to the RA senseamplifier (and LA sense amplifier if provided), RV sense amplifier andLV sense amplifier. Again, sense electrode selection and control circuit53 selects conductors and associated sense electrode pairs to be coupledwith the atrial and ventricular sense amplifiers within the outputamplifiers circuit 51 and sense amplifiers circuit 55 for accomplishingRA, LA, RV, and LV sensing along desired unipolar and bipolar sensingvectors.

Right atrial depolarizations or P-waves in the RA-SENSE signal that aresensed by the RA sense amplifier result in a RA-EVENT signal that iscommunicated to the digital controller/timer circuit 43. Similarly, leftatrial depolarizations or P-waves in the LA-SENSE signal that are sensedby the LA sense amplifier, if provided, result in a LA-EVENT signal thatis communicated to the digital controller/timer circuit 43. Ventriculardepolarizations or R-waves in the RV-SENSE signal are sensed by aventricular sense amplifier result in an RV-EVENT signal that iscommunicated to the digital controller/timer circuit 43. Similarly,ventricular depolarizations or R-waves in the LV-SENSE signal are sensedby a ventricular sense amplifier result in an LV-EVENT signal that iscommunicated to the digital controller/timer circuit 43. The RV-EVENT,LV-EVENT, and RA-EVENT, LA-SENSE signals may be refractory ornon-refractory and can inadvertently be triggered by electrical noisesignals or aberrantly conducted depolarization waves rather than trueR-waves or P-waves.

The techniques described in this disclosure, including those attributedto the IMD 16, the computing apparatus 140, and/or various constituentcomponents, may be implemented, at least in part, in hardware, software,firmware, or any combination thereof. For example, various aspects ofthe techniques may be implemented within one or more processors,including one or more microprocessors, DSPs, ASICs, FPGAs, or any otherequivalent integrated or discrete logic circuitry, as well as anycombinations of such components, embodied in programmers, such asphysician or patient programmers, stimulators, image processing devices,or other devices. The term “module,” “processor,” or “processingcircuitry” may generally refer to any of the foregoing logic circuitry,alone or in combination with other logic circuitry, or any otherequivalent circuitry.

Such hardware, software, and/or firmware may be implemented within thesame device or within separate devices to support the various operationsand functions described in this disclosure. In addition, any of thedescribed units, modules, or components may be implemented together orseparately as discrete but interoperable logic devices. Depiction ofdifferent features as modules or units is intended to highlightdifferent functional aspects and does not necessarily imply that suchmodules or units must be realized by separate hardware or softwarecomponents. Rather, functionality associated with one or more modules orunits may be performed by separate hardware or software components orintegrated within common or separate hardware or software components.

When implemented in software, the functionality ascribed to the systems,devices and techniques described in this disclosure may be embodied asinstructions on a computer-readable medium such as RAM, ROM, NVRAM,EEPROM, FLASH memory, magnetic data storage media, optical data storagemedia, or the like. The instructions may be executed by processingcircuitry and/or one or more processors to support one or more aspectsof the functionality described in this disclosure.

ILLUSTRATIVE EMBODIMENTS

Embodiment 1: A system for use in cardiac evaluation comprising:

electrode apparatus comprising a plurality of external electrodes tomonitor electrical activity from tissue of a patient;

communication interface to receive cardiac information from at least onemedical device; and

a computing apparatus comprising processing circuitry and operablycoupled to the electrode apparatus and the communication interface, thecomputing apparatus configured to:

monitor electrical activity using the plurality of external electrodes,

receive supplemental cardiac data from at least one medical device viathe communication interface, and

synchronize the monitored electrical activity or data based on themonitored electrical activity to the supplemental cardiac data resultingin synchronized cardiac information.

Embodiment 2: A method for use in cardiac evaluation comprising:

monitoring electrical activity from tissue of a patient using aplurality of external electrodes;

receiving supplemental cardiac data from at least one medical device;and

synchronizing the monitored electrical activity or data based on themonitored electrical activity to the supplemental cardiac data resultingin synchronized cardiac information.

Embodiment 3: The system or method as set forth in any one ofembodiments 1-2, wherein the supplemental cardiac data comprises one ormore markers indicative of the occurrence of cardiac events.

Embodiment 4: The system or method as set forth in embodiment 3, whereinthe one or more markers comprise one or more markers indicative anintrinsic atrial depolarization, atrial pace, a premature atrialcomplex, an intrinsic ventricular depolarization, ventricular pace, apremature ventricular complex, ventricular repolarization during anintrinsic or paced ventricular event, effective ventricular or atrialcapture, ineffective ventricular or atrial capture, heart valve closure,heart valve opening, systole, and diastole

Embodiment 5: The system or method as set forth in any one ofembodiments 1-4, wherein the supplemental cardiac data is representativeof at least one of cardiac electrical signals, cardiac sounds, cardiacpressures, blood flow, and an estimated instantaneous flow waveformprovided by a left ventricular assist device.

Embodiment 6: The system or method as set forth in any one ofembodiments 1-5, wherein the system further comprises a displaycomprising a graphical user interface to present information for use inassisting a user in at least one of assessing a patient's cardiachealth, evaluating and adjusting cardiac therapy delivered to a patient,and navigating at least one implantable electrode to a region of thepatient's heart, wherein the computing apparatus operably coupled to thedisplay and further configured to execute or the method furthercomprises displaying, on a graphical user interface, at least part ofthe monitored electrical activity or data based thereon annotated withat least part of the supplemental cardiac data.

Embodiment 7: The system or method as set forth in any one ofembodiments 1-6, wherein the computing apparatus is further configuredto execute or the method further comprises determining at least oneinterval between a first event indicated by the monitored electricalactivity and a second event indicated by the supplemental cardiac data.

Embodiment 8: The system or method as set forth in any one ofembodiments 1-7, wherein the computing apparatus is further configuredto execute or the method further comprises modifying the monitoredelectrical activity based on the supplemental cardiac data.

Embodiment 9: The system or method as set forth in embodiment 8, whereinmodifying the monitored electrical activity based on the supplementalcardiac data comprises disregarding the monitored electrical activityfor a selected period of time following a ventricular pace indicated bythe supplemental cardiac data.

Embodiment 10: The system or method as set forth in any one ofembodiments 1-9, wherein the at least one medical device comprises animplantable medical device.

Embodiment 11: The system or method as set forth in any one ofembodiments 1-10, wherein the at least one medical device comprises atleast one of a cardiac pacing device, a left ventricular assist device,cardioverter-defibrillator, a subcutaneous monitoring device, and anintracardiac pressure sensor.

Embodiment 12: A system for use in cardiac evaluation comprising:

electrode apparatus comprising a plurality of external electrodes tomonitor electrical activity from tissue of a patient;

communication interface to receive cardiac information from at least onemedical device;

a display comprising a graphical user interface to present informationfor use in assisting a user in at least one of assessing a patient'scardiac health and evaluating and adjusting cardiac therapy delivered toa patient, and

a computing apparatus comprising processing circuitry and operablycoupled to the electrode apparatus and the communication interface, thecomputing apparatus configured to:

monitor electrical activity using the plurality of external electrodes,

receive supplemental cardiac data from at least one medical device viathe communication interface,

synchronize the monitored electrical activity or data based on themonitored electrical activity to the supplemental cardiac data resultingin synchronized cardiac information, and

display, on the graphical user interface, at least part of the monitoredelectrical activity or data based thereon annotated with at least partof the supplemental cardiac data.

This disclosure has been provided with reference to illustrativeembodiments and is not meant to be construed in a limiting sense. Asdescribed previously, one skilled in the art will recognize that othervarious illustrative applications may use the techniques as describedherein to take advantage of the beneficial characteristics of theapparatus and methods described herein. Various modifications of theillustrative embodiments, as well as additional embodiments of thedisclosure, will be apparent upon reference to this description.

What is claimed is:
 1. A system for use in cardiac evaluationcomprising: electrode apparatus comprising a plurality of externalelectrodes to monitor electrical activity from tissue of a patient;communication interface to receive cardiac information from at least onemedical device; and a computing apparatus comprising processingcircuitry and operably coupled to the electrode apparatus and thecommunication interface, the computing apparatus configured to: monitorelectrical activity using the plurality of external electrodes, receivesupplemental cardiac data from at least one medical device via thecommunication interface, and synchronize the monitored electricalactivity or data based on the monitored electrical activity to thesupplemental cardiac data resulting in synchronized cardiac information.2. The system of claim 1, wherein the supplemental cardiac datacomprises one or more markers indicative of the occurrence of cardiacevents.
 3. The system of claim 2, wherein the one or more markerscomprise one or more markers indicative an intrinsic atrialdepolarization, atrial pace, a premature atrial complex, an intrinsicventricular depolarization, ventricular pace, a premature ventricularcomplex, ventricular repolarization during an intrinsic or pacedventricular event, effective ventricular or atrial capture, ineffectiveventricular or atrial capture, heart valve closure, heart valve opening,systole, and diastole
 4. The system of claim 1, wherein the supplementalcardiac data is representative of at least one of cardiac electricalsignals, cardiac sounds, cardiac pressures, blood flow, and an estimatedinstantaneous flow waveform provided by a left ventricular assistdevice.
 5. The system of claim 1, the system further comprising adisplay comprising a graphical user interface to present information foruse in assisting a user in at least one of assessing a patient's cardiachealth, evaluating and adjusting cardiac therapy delivered to a patient,and navigating at least one implantable electrode to a region of thepatient's heart, wherein the computing apparatus operably coupled to thedisplay and further configured to: display, on the graphical userinterface, at least part of the monitored electrical activity or databased thereon annotated with at least part of the supplemental cardiacdata.
 6. The system of claim 1, wherein the computing apparatus isfurther configured to determine at least one interval between a firstevent indicated by the monitored electrical activity and a second eventindicated by the supplemental cardiac data.
 7. The system of claim 1,wherein the computing apparatus is further configured to modify themonitored electrical activity based on the supplemental cardiac data. 8.The system of claim 7, wherein modifying the monitored electricalactivity based on the supplemental cardiac data comprises disregardingthe monitored electrical activity for a selected period of timefollowing a ventricular pace indicated by the supplemental cardiac data.9. The system of claim 1, wherein the at least one medical devicecomprises an implantable medical device.
 10. The system of claim 1,wherein the at least one medical device comprises at least one of acardiac pacing device, a left ventricular assist device,cardioverter-defibrillator, a subcutaneous monitoring device, and anintracardiac pressure sensor.
 11. A method for use in cardiac evaluationcomprising: monitoring electrical activity from tissue of a patientusing a plurality of external electrodes; receiving supplemental cardiacdata from at least one medical device; and synchronizing the monitoredelectrical activity or data based on the monitored electrical activityto the supplemental cardiac data resulting in synchronized cardiacinformation.
 12. The method of claim 11, wherein the supplementalcardiac data comprises one or more markers indicative of the occurrenceof cardiac events.
 13. The method of claim 12, wherein the one or moremarkers comprise one or more markers indicative an intrinsic atrialdepolarization, atrial pace, a premature atrial complex, an intrinsicventricular depolarization, ventricular pace, a premature ventricularcomplex, ventricular repolarization during an intrinsic or pacedventricular event, effective ventricular or atrial capture, ineffectiveventricular or atrial capture, heart valve closure, heart valve opening,systole, and diastole
 14. The method of claim 11, wherein thesupplemental cardiac data is representative of at least one of cardiacelectrical signals, cardiac sounds, cardiac pressures, blood flow, andan estimated instantaneous flow waveform provided by a left ventricularassist device.
 15. The method of claim 11, The method further comprisinga display comprising a graphical user interface to present informationfor use in assisting a user in at least one of assessing a patient'scardiac health, evaluating and adjusting cardiac therapy delivered to apatient, and navigating at least one implantable electrode to a regionof the patient's heart, wherein the computing apparatus operably coupledto the display and further configured to: display, on the graphical userinterface, at least part of the monitored electrical activity or databased thereon annotated with at least part of the supplemental cardiacdata.
 16. The method of claim 11, wherein the computing apparatus isfurther configured to determine at least one interval between a firstevent indicated by the monitored electrical activity and a second eventindicated by the supplemental cardiac data.
 17. The method of claim 11,wherein the computing apparatus is further configured to modify themonitored electrical activity based on the supplemental cardiac data.18. The method of claim 17, wherein modifying the monitored electricalactivity based on the supplemental cardiac data comprises disregardingthe monitored electrical activity for a selected period of timefollowing a ventricular pace indicated by the supplemental cardiac data.19. The method of claim 11, wherein the at least one medical devicecomprises an implantable medical device.
 20. The method of claim 11,wherein the medical device comprises at least one of a cardiac pacingdevice, a left ventricular assist device, cardioverter-defibrillator, asubcutaneous monitoring device, and an intracardiac pressure sensor. 21.A system for use in cardiac evaluation comprising: electrode apparatuscomprising a plurality of external electrodes to monitor electricalactivity from tissue of a patient; communication interface to receivecardiac information from at least one medical device; a displaycomprising a graphical user interface to present information for use inassisting a user in at least one of assessing a patient's cardiac healthand evaluating and adjusting cardiac therapy delivered to a patient, anda computing apparatus comprising processing circuitry and operablycoupled to the electrode apparatus and the communication interface, thecomputing apparatus configured to: monitor electrical activity using theplurality of external electrodes, receive supplemental cardiac data fromat least one medical device via the communication interface, synchronizethe monitored electrical activity or data based on the monitoredelectrical activity to the supplemental cardiac data resulting insynchronized cardiac information, and display, on the graphical userinterface, at least part of the monitored electrical activity or databased thereon annotated with at least part of the supplemental cardiacdata.